Automatic drain valve

ABSTRACT

An automatic float-activated drain valve for a liquid reservoir used in the accumulation of condensable materials and other contaminants from pneumatic systems and the like. The float is connected by a flexible tether to a lever arm which opens a pilot valve when the reservoir fills with water and the float moves to the top of the reservoir. The pilot valve permits air pressure to flow to an actuator which opens the drain valve.

TECHNICAL FIELD

This invention relates generally to float-activated drain systems for liquid reservoirs, and more particularly to an automatic drain valve for traps used in the accumulation of condensable materials and other contaminants from pneumatic systems and the like.

BACKGROUND OF THE INVENTION

It is conventional to use filters and separators for removing foreign objects, and condensing and removing water and other condensable liquids, from pressurized air lines and the like. Typically, such filters include an air inlet, an air outlet and a filtering element mounted between these elements in the flow path. Such filters also include a reservoir or filter bowl through which the air flow is at least partially passed causing the moisture and other condensables in the air to be coalesced and condensed on the inside surface of the reservoir or bowl. The force of gravity causes such condensed materials to accumulate at the bottom of the reservoir together with any other foreign objects. Periodically, this accumulated material must be discharged when the reservoir or filter bowl has become full of material.

Various types of drain systems with automatic valves have been devised to discharge such accumulated material. Examples of such devices are shown in U.S. Pat. No. 3,993,090 issued to Paul M. Hankinson, and in U.S. Pat. Nos. 4,444,217, 4,562,855, and 4,574,829 all of which are issued to Ernie W. Cummings and Nick Valk. All the above patents disclose the use of magnetic coupling members within a reservoir which translate the movement of a float within the reservoir to open and close a pilot valve which in turn causes the opening and closing of a drain valve. When the reservoir fills with water and the float rises the magnetic coupling members interact to open the pilot valve and thereby open the drain valve. When the float returns to the bottom of the reservoir the magnetic coupling members interact to cause the pilot valve to close and thereby close the drain valve.

A problem can occur in the devices described in the above patents when the magnetic coupling members and related moving parts become coated with corrosion or other or deposits of contaminates which may be present in the water. Such accumulations can cause a failure of the float to rise properly or the pilot valve may stick in either the open or closed position. The present invention eliminates the need for magnetic coupling devices which may be prone to sticking when accumulations of corrosion and contaminates are present on the surface of the magnetic coupling members and other related working parts of the drain valve system.

OBJECTS OF THE INVENTION

An object of this invention is to provide an automatic float activated drain valve for a reservoir which uses a minimum number of moving parts located within the reservoir.

Another object of this invention is to provide an automatic float actuated drain valve which is greatly reduces the chances of sticking due to accumulations of corrosion and contaminates on the surfaces of the moving parts of the actuation system.

Still another object of the invention is to provide an automatic float actuated drain valve which is simple, and easy to manufacture and service.

These and other objects of the invention will become more fully apparent in the following description and the attached drawings:

SUMMARY OF THE INVENTION

This invention is an automatic drain valve system for reservoirs for accumulating liquids in a pneumatic system comprising: a reservoir having a top, a bottom and sidewall means extending therebetween, the reservoir having an inlet opening and an outlet opening connected to a pneumatic system and said reservoir having an drain in the bottom thereof; a drain valve for the reservoir mounted external of the reservoir and connected to the outlet drain; a pneumatic valve operator mounted external to said reservoir and attached to said drain valve for opening and closing the valve; a buoyant float positioned within the reservoir responsive to liquid level in the reservoir to move between a high position and a low position within the reservoir; a normally closed pilot valve mounted in the top of the reservoir; actuation lever means having a first end operatively connected to the pilot valve and extending downwardly inside the reservoir with a second end positioned near the bottom of the reservoir when the float is in a low position within the reservoir; flexible tether means connecting the second end of the actuation lever means to the float, said tether means being of sufficient length that it will permit the float to rise a certain distance from a low position within the reservoir before exerting a pull on the actuation lever means and thereafter moving to a high position within the reservoir while exerting a pull on said actuation lever means to cause the pilot valve to open; and pneumatic means connected between the pilot valve and the valve operator to cause the valve operator to open the drain valve when the pilot valve is opened by the float rising to a high position in the reservoir, and to close the drain valve when the pilot valve is closed by the float sinking to a low position in the reservoir.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view a reservoir using the invention taken on line 1--1 of FIG.

FIG. 2 is a horizontal cross-sectional view of a reservoir of the invention taken on line 2--2, of FIG. 1;

FIG. 3 is a plan view of a casting which can be used as either the top of bottom of the reservoir of the invention; and

FIG. 4 is a vertical cross-sectional view of the reservoir of the invention similar to FIG. 1 but showing a float in a raised position inside the reservoir with the reservoir filled with water.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings as shown in FIGS. 1 through 4, a liquid accumulation reservoir assembly for a pneumatic system is indicated generally by the numeral 10. The reservoir assembly 10 may be connected to any conventional pneumatic system (not shown). Such a pneumatic system would normally include a compressor pump or other source of pneumatic pressure, a pressure tank for storing compressed air or other gas and a series on pneumatic lines linking, the pump, the storage tank and any other equipment used therewith and the system would also have pneumatic lines linking the systems to the reservoir assembly 10.

The reservoir assembly 10 has a reservoir 12 which is formed from a cylindrical sidewall 14, a top 16 and a bottom 18 which are formed as substantially identical rib reinforced castings except for different inlet and outlet ports drilled therein.

The top 16 and bottom 18 sealingly engage the top and bottom edges respectively of the sidewall 14 and form a closed container for accumulating water and other residual materials that form in a pneumatic system. The top 16 and bottom 18 are clamped against the edges of the sidewall 14 by a four bolts 20 which pass through holes 22 in the top 16 and bottom 18.

The bottom 18 has an inlet port 24 which receives an inlet line 26 connected to an outlet port on a compressed air storage tank (not shown). The line 26 permits condensed water to drain from the storage tank into the reservoir 12.

An outlet drain port 28 is located in the bottom 18 to drain water from the reservoir 12 periodically. The drain port 28 is connected to a drain line 30 in which is located a valve 32 which is opened and closed by a valve arm 34. The valve arm 34 is operated by a piston rod 36 and a piston 37 of a pneumatic actuator 38 which is attached by a bracket 40 to the bottom 18. The piston 37 and piston rod is biased upwardly by a return spring 39 to hold the valve 32 in a normally closed position.

In the top 16 of the reservoir 12, a pilot valve inlet port 42 connects through a pilot valve 44 to a pilot valve outlet port 46 connected through line 48 to the actuator 38. The inlet port 42 is connected through a line 48' passing through a filter 40 to a source of pneumatic pressure in a pneumatic system.

A lever arm bracket 52 is attached by screws 54 to the bottom of the top 16 in alignment with the pilot valve 44. The lever arm bracket 52 retains a toggle linkage 56 having one end connected to a moveable valve closure member 58 and the other end connected to a lever arm 60 which is pivotally connected at a pivot pin 62 to the lever arm bracket 52. The lever arm 60 is substantially L-shaped and extends downwardly within the reservoir 12 and then substantially horizontally across the bottom of the reservoir 12. A flexible tether 64 has one end connected to the end of the lever arm 60 and the other end connected to the bottom of a float 66 by a screw 68.

As shown in FIG. 1, when the reservoir 12 is empty of liquid or at a very low level float 66 is at the bottom of the reservoir and the lever arm is at such a position that the pilot valve 44 is closed. As long as the pilot valve 44 is closed, the drain valve 32 remains closed. When the reservoir 12 is sufficiently filled with water as shown in FIG. 4, the float 66 rises to the top of the reservoir 12 and the tether 64 pulls the lever arm 60 upward causing it to pivot around pivot pin 62 and move the toggle linkage 56 to a position where it opens the pilot valve 44. Opening of the pilot valve 44 causes air pressure to pass through the line 48 into the upper end of the actuator 38 and thereby overcome the upward force of the spring 39 and move the piston 37, the piston rod 36 and valve arm 34 downwardly to open the valve 32 and allow the water to drain through the line 30 until the reservoir 12 is at least substantially empty. The actuator 38 has a has an upper port 70 at the upper end and a lower port 72 at the lower end. The lower port 72 serves as an exhaust line when pressure is flowing through the line 48 into the upper end of the actuator 38 and permits air to flow back into the lower end of the actuator 38 when the piston rod 36 returns to the raised position shown in FIG. 1 in which the valve 32 is closed. The upper port 70 permits air to be exhausted from the upper end of the actuator when the piston 37 is moved upwardly by the return spring 39.

As the water level drops, the float 66 returns to the bottom of the reservoir and the lever arm 60 returns to the position shown in FIG. 1. This causes closing of the pilot valve 44 and in turn the drain valve 32. It should be understood that even through the upper port 70 remains open at all times, when the pilot valve 44 is open and air flows though the line 48 into the upper end of the actuator, there is still a sufficient build-up of pressure to force the piston 37 downwardly to open the valve 32.

The above described process is automatically repeated each time the reservoir fills with water.

It is understood that the reservoir can have additional ports to those shown in FIGS. 1 through 4 and can be connected to additional lines in a pneumatic system depending upon the overall arrangement of the particular system with which the reservoir 12 is used. It should also be understood that various other minor changes be made in the arrangement of the lever arm, the float, and the pilot valve without departing from the scope of the invention. 

We claim:
 1. An automatic drain valve system for reservoirs containing liquids comprising:a reservoir provided with an inlet opening and an outlet drain; a drain valve for the reservoir mounted external of the reservoir and connected to the outlet drain; a pneumatic valve operator mounted external to said reservoir and attached to said drain valve for opening and closing the valve; a buoyant float positioned within the reservoir responsive to liquid level in the reservoir to move between a high position and a low position within the reservoir; a normally closed pilot valve mounted in fixed relationship to the reservoir; actuation lever means having a first end operatively connected to the pilot valve and extending inside the reservoir with a second end positioned near the bottom of the reservoir when the float is in a low position within the reservoir; flexible tether means connecting the second end of the actuation lever means to the float, said tether means being of sufficient length that it will permit the float to rise a certain distance from a low position within the reservoir before exerting a pull on the actuation lever means and thereafter moving to a high position within the reservoir while exterting a pull on said actuation lever means to cause the pilot valve to open; andpneumatic means connected between the pilot valve and the valve operator to cause the valve operator to open the drain valve when the pilot valve is opened by the float rising to a high position in the reservoir, and to close the drain valve when the pilot valve is closed by the float sinking to a low position in the reservoir.
 2. The drain valve system claimed in claim 1 wherein the pilot valve is located in an upper portion of the reservoir and the actuation lever means extends downwardly to a position near the bottom the reservoir then toward the center of the reservoir to a position between the bottom of the reservoir and the float.
 3. The drain valve system claimed in claim 1 wherein the actuation lever means comprises a substantially L-shaped lever connected through a toggle linkage to a valve stem.
 4. The drain valve system claimed in claim 1 wherein the outlet drain is located in the bottom of the reservoir.
 5. The drain valve system claimed in claim 1 wherein inlet opening is located at the bottom of the reservoir.
 6. The drain valve system claimed in claim 1 wherein the pilot valve is located in the top of the reservoir.
 7. The drain valve system claimed in claim 1 wherein the drain valve is located in close proximity to the bottom of the reservoir.
 8. An automatic outlet drain valve system for reservoirs for accumulating liquids in a pneumatic system comprising:a reservoir having a top, a bottom and sidewall means extending therebetween, the reservoir having an inlet opening and an outlet opening connected to a pneumatic system and said reservoir having an drain in the bottom thereof; a drain valve for the reservoir mounted external of the reservoir and connected to the outlet drain; a pneumatic valve operator mounted external to said reservoir and attached to said drain valve for opening and closing the valve; a buoyant float positioned within the reservoir responsive to liquid level in the reservoir to move between a high position and a low position within the reservoir; a normally closed pilot valve mounted in the top of the reservoir; actuation lever means having a first end operatively connected to the pilot valve and extending downwardly inside the reservoir with a second end positioned near the bottom of the reservoir when the float is in a low position within the reservoir; flexible tether means connecting the second end of the actuation lever means to the float, said tether means being of sufficient length that it will permit the float to rise a certain distance from a low position within the reservoir before exerting a pull on the actuation lever means and thereafter moving to a high position within the reservoir while exterting a pull on said actuation lever means to cause the pilot valve to open; andpneumatic means connected between the pilot valve and the valve operator to cause the valve operator to open the drain valve when the pilot valve is opened by the float rising to a high position in the reservoir, and to close the drain valve when the pilot valve is closed by the float sinking to a low position in the reservoir.
 9. The drain valve system claimed in claim 8 wherein the actuation lever means extends downwardly to a position near the bottom the reservoir then toward the center of the reservoir to a position between the bottom of the reservoir and the float.
 10. The drain valve system claimed in claim 8 wherein the actuation lever means comprises a substantially L-shaped lever connected through a toggle linkage to a valve stem.
 11. The drain valve system claimed in claim 8 wherein top and bottom are of substantially identical shape but have different ports drilled therein.
 12. The drain valve system claimed in claim 8 wherein the sidewall means is of cylindrical shape. 